Pediatric emergency medicine trisk 1508 1508
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Proarrhythmic agents (Class 1A and 1C antiarrhythmics), vasodilators,
depressants
Conditions that mimic syncope
Seizures
Migraine
Conversion disorder a
Hyperventilation
Pseudoseizures
Intentional strangulation (e.g., “choking game”)
Narcolepsy
a Common
causes of syncope.
life-threatening causes.
b Potentially
It is crucial to obtain a full family history in patients suspected of having
LQTS. Some clinical features such as QT morphologic characteristics, the
response of the QT interval to exercise, triggers of arrhythmia, and response to
therapies vary according to the disease-associated gene. In LQTS, recent and
frequent syncopal episodes between the ages of 10 and 12 years, QTc
prolongation >530 msec, and male gender are predictive of risk for aborted
cardiac arrest and sudden cardiac death during adolescence.
Brugada Syndrome
In this heritable disorder, there is an abnormality in the cardiac sodium channel
that results in ST-segment elevation in anterior precordial leads (V1 and V2) with
a susceptibility to polymorphic ventricular tachycardia. The ECG pattern is
diagnostic, but may be present only intermittently, and may change over time. If
the arrhythmia degenerates to ventricular fibrillation, it may lead to sudden death;
if it terminates, the patient may have only syncope.
Structural Heart Disease
Congenital heart conditions that interfere with cardiac output may result in
syncope. Such structural problems include hypertrophic obstructive
cardiomyopathy (HOCM), aortic valve stenosis, and coronary anomalies that
cause cardiac ischemia. Functionally, pulmonary hypertension may cause similar
results. As with other cardiac causes of syncope, chest pain, dizziness, and
dyspnea on exertion are concerning symptoms that should prompt further
evaluation.
HOCM is a genetic disorder that affects the proteins of the cardiac sarcomere.
In this condition, the hypertrophied basal interventricular septum partially blocks
